1. Field of the Invention
The present invention relates to a xanthine oxidase inhibitor having an effective component derived from plants.
2. Related Art Statement
Xanthine oxidase that is contained at a great amount in liver, small intestine mucous membrane, and milk of mammals produces uric acid via xanthine from hypoxanthine in the final step of the degradation pathway of purine compounds.
Increase in concentrations of blood uric acid causes various diseases such as gout as hyperuricemia, therefore, uric acid producing inhibitors, that is, the xanthine oxidase inhibitors are clinically administered in order to treat hyperuricemia. Development of physiologically active substances capable of repressing the activity of xanthine oxidase has been attracting attention.
Until now, a number of compounds have been reported which have a xanthine oxidase inhibiting effect. Many of such compounds, however, were synthesized by chemical procedures, and it could never be said that they were highly safety for human bodies. Recently, from a viewpoint of the safety for human bodies, there have been disclosed xanthine oxidase inhibitors derived from natural sources (Japanese Patent Laid-open Publications 1993-244963, 1997-202733, and others). However, they do not have a sufficient effect of inhibiting xanthine oxidase to a satisfactory extent.
An object of the present invention is to provide a xanthine oxidase inhibitor, which has as an effective component highly safe components derived from natural sources and a superior effect of inhibiting the xanthine oxidase activity.
The inventors have examined plants worthy of utilizing as a xanthine oxidase inhibitor as to plants which have been provided for food for many years and found safe for human bodies. In consequence, it has been found that extract of Lagerstroemia speciosa, a plant belonging to the genus Lagerstroemia in the family Lythraceae, exhibits a strong effect of inhibiting xanthine oxidase, which leads to achieving the present invention.
Accordingly, a xanthine oxidase inhibitor of the present invention is characterized by containing as an effective component extracted components from xe2x80x9cLagerstroemia speciosaxe2x80x9d belonging to the genus Lagerstroemia.
This xe2x80x9cLagerstroemia speciosaxe2x80x9d grows in tropical regions including, for example, the Philippines, and is called banaba. Its extracted liquid is taken daily as tea in the Philippines and others, therefore the safety for human bodies is assured.